The present invention relates to article assembling method and device capable of easily assembling articles without any contamination or damage of the articles even with a rather inferior accuracy of positioning of an article with respect to another article.
In general, an assembly process includes operations for fitting articles to objects. Fitting of precision parts in particular requires a high degree of positioning accuracy. In order to facilitate fitting of a precision part, Japanese Patent Unexamined Publication No. 51-55076 discloses a device in which a mechanism for holding an article is coupled to a positioning mechanism through an elastic member so that the article can easily be fitted to an object even when the positioning mechanism has a rather low positional resolution and accuracy.
A device is also known for fitting a disk on a spindle of a magnetic disk file assembly, in which, as shown in Nikkei Mechanical (No. 328, 1983), a disk mounting hand provided with a sensor and an inching mechanism holds and fits the disk on the spindle. The mounting hand has a suction pad capable of sticking to the disk and a 6-axis force sensor provided at a level above that of the suction pad so as to oppose the suction pad across the spindle hole formed in the disk.
Japanese Patent Unexamined Publication Nos. 62-211236 and 62-255335 disclose devices which are capable of holding plate-like members such as semiconductor wafer in a floating or non-contacting manner by combination of suction and jetting actions of a fluid.
The known device disclosed in Japanese Patent Unexamined Publication No. 51-55076 on the one hand offers an advantage that an article can be fitted easily without requiring high positioning accuracy but, on the other hand, poses a problem in that the article is undesirably forcibly pressed against or rubbed by a part to which the article is to be fitted by the force applied through the elastic member when the deviation of the article from the correct fitting position exists, resulting in generation of dust or scuffing and, hence, in contamination or damage of the article.
The art shown in Nikkei Mechanical (No. 328, 1983) employs a compliance mechanism which performs positioning of articles in the directions perpendicular to the fitting or insertion direction so as to avoid any rubbing or scuffing during fitting. More specifically, the compliance mechanism includes a sensor capable of sensing any reaction force generated as a result of contact between the article and the object and an inching mechanism capable of operating in response to the output from the sensor indicative of the occurrence of such contact so as to finely adjust the position of the article thereby preventing the article from being strongly pressed against the object. In this system, however, a contact inevitably takes place between the article, i.e., a disk, and the object, i.e., the spindle. In addition, a force greater than the resolution (several tens of grams) of the sensor is applied to the disk and a further greater force is applied to the disk due to delay of the action of the inching mechanism after the contact is sensed by the sensor. Consequently, damaging of the disk or the spindle and, thus, generation of dust is unavoidable. In general, assembly of precision parts strictly requires elimination of contamination and damage.
For instance, a disk assembling process in the production of a magnetic disk device requires that generation of dust is minimized. Usually, a reading/ writing head is held in a floating position at a level 0.25 to 0.5 mm above a rotating disk. Any dust existing between the head and the disk causes a head crush which disables the head to read and write.